Paper manufacture



Jan. 31, .1933. J. H. SWAN, an

PAPE'R MANUFACTURE Filed Aug. so, 1929 Qwomtoc teriorate on standing. for considerable inter-' embodiment of the invention Patented Jan. 31, 1933 UNITED STATES,

PATENT OFFICE JOSEPH H. SWAN, 3D, OF MIDDLETOWN, OHIO, ASSIGNOR TO THE GARDNER-RICHARDSON COMPANY, OF HIDDLETOWN, OHIO, A CORPORATION OF OHIO PAPER MAHUFACTURE Application filed Kugust 30, 1929. g Serial No. 889,421.

This invention relates to the manufacture of paper, and particularly to the manufacture of board adapted for use inthe making of containers and the like.

One of the principal objects oiLtheinvention is to provide a paper or board which is grease proof and moisture proof, is sufliciently flexible and elastic to permit bending, is"

substantially odorless and tasteless, stands up well in use and does not objectionably devals of time, and is commercially economical.

Another object of the invention is to provide a superior grease proofing and moisture proofing coating for paper or board of this character.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and appended, claims.

In the drawing, which discloses a preferred This invention is particularly applicable to the rendering of paper or board, such as container board, impervious to grease, so that containers made therefrom may be used for packaging greasy or oily substances which would otherwise penetrate through the package. When such a product is used for packaging foodstufl's, such for example as peanut butter or the like, it is particularly desirable that the surface of the container board be substantially tasteless and odorless. The coating should be of such character as to form an impervious layer on the board without pin holes which destroy the effectiveness of the coating, and it should be'sufliciently flexible and elastic to permit the bending durable'nature, and one that will stand up well in use and will not objectionably deteriorate uponstanding for considerable intervals of time. In accordance with the pres ent invention, a coating composition is provided which has superior qualities, and a coated paper product is formed which is unusually efiicacious in satisfying the above requirements.

Referring to the drawing, the paper or board to be coated is carried by a real 10 supported in suitable bearings on a frame 11 mounted on the foundation. The paper or board indicated at 12 passes over a guide roll 13 and thence between the ni of driven rolls 14 and 15 which form a coating press. Each ofthe rolls 14 and 15 is mounted in slidable 19and a lock nut 20 serving to permit desired horizontal adjustment of the bearings. This permits the rolls 14 and 15 to be adjusted relatively to each other to bring the rolls into contact with the desired operating ressure, forming a trough indicated at 21 a ove the nip WhlCh is closed at each end b a sultable deckle member 22. Coating so ution of a grease proofin nature is supplied to the trough 21 by pipe 23 having a control valve 24. The paper 12 passing through the trough and between the nip of the rolls receives a coating on one side thereof, the thickness of the coating being regulated by the pressure at the nip.

The grease proofing coating compo s1t1on applied at this point comprises glycerine, a water solution of sodium silicate, and an alkali metal compound adapted to maintain the coating'in an alkaline condition to prevent deterioration of the coating film. The addition of glycerine to the sodium s1l1cate imparts characteristics of flexibility and resiliency to the coating and'tends to prevent cracking thereof when the board is bent 1n the formation of the container, and also 1mproves the spreading and the grease proofing qualities of the coating with the productlon of a substantially impervious film or layer. Other polyhydric alcohols, for example glycols such as ethylene glycol, can be used with satisfactory results in substantially the same of sodium or potassium are preferred to ammonia, inasmuch as the latter is subject to evaporation while the former retain the coating permanently in the desired stable condition.

In the preparation of the coating composition, the alkali metal silicate is first made up in a relatively concentrated water solution. Thus where sodium silicate is used, a solution containing in excess of about 15% sodium silicate is preferred. Satisfactory results may be secured with solutions containing from about 15% to 60% sodium'silicate by weight. The alkali metal compound is also made up in water solution, or may be dissolved directly in the sodium silicate solution. These ingredients are then mixed with the glycerine. Satisfactory results have been secured with compositions containing from 15% to by volume of glycerine, and to 85% by volume of a water solution of sodium silicate of the above proportions, this composition containing about 1 to 2% by weight of an alkali metal compound adapted to preserve the alkalinity of the coating.

As an example of a very satisfactory coating composition, the following is'mentioned: Sodium silicate solution of about 38% strength and glycerine are mixed in the proportions of about 25% by volume of glycerine and 75% by volume of the sodium silicate solution. To this composition is added about 1% to 2% by weight of sodium carbonate. The board 12 with the coating on the upper surface thereof then passes across a plurality of rotatable drying drums 28 mounted in bearings 29 carried by a frame 30, the under surface of the board contacting with the upper portions of the drying drums. These may be the conventional steam heated drying cylinders, and are maintained atthe usual temperatures which is customary in the drying of paper. The board'then passes around a strain roll 31 so that the coated surface is then underneath, and returns with the upper uncoated surface in contact with a portion of the bottom of the surfaces of the drying drums 28. As many drying drums may be provided as is necessary to secure the proper drying of the coating.

A board which is given only a grease proofing coating is subject to deterioration when exposed to the atmosphere, and particularly when exposed to water or dampnesi In accordance with the present invention, an overlying Water insoluble wax coat is applied over the grease proof coating. Very satisfactory results are secured with paraflin, beeswax, montan wax, or other well known water insoluble waxes. From the standpoint of economy and ease of application paraffin is preferred for this purpose. This combination of an oil insoluble coat with a water insoluble overcoat applied as herein described terials or foodstuffs to be packaged tasteless and odorless.

For the purpose of applying the top wax coat, a press comprising a lower roll 35 and an upper contacting roll 36 with which'the under coated surface of the web 12 contacts, is provided. The lower roll 35 dips within a trough 37 containing a bath of paraffin 38 maintained in molten condition by a suitable steam coil 39. Rotation of roll 35 within the bath of molten parafiin provides a surface film upon this roll which is transferred to the contacting roll 36 and thence to the paper web in the form of a thin film over the base coating. The coated web then passes over a suitable guide roll 40, or additional drying means as desired, and thence is wound on a reel 41.

In order to further improve the quality of the paper product, the paper or board is first subjected to a sizing treatment before the coating is applied. Thus the board, or the layer of the board forming the outer surface which receives the coating is preferably a hard sized sheet, or one which has been made up from paper stock to which a sufficient quantity of size, such as rosin size or parafiinsize, has been added as to materially retard the rate at which water or ink penetrates into the sheet. Very satisfactory results are secured by forming a sheet from paper stock to which rosin size has been added in the beater in the proportion of about 80 pounds of size to 1200 pounds of pulp. A sheet which will stand up for approximately five minutes or over in the water drop test, which means that water will not penetrate the sheet in that time, is satisfactory. Or the sheet may be given a surface sizing by an application of a size to the surface of the formed web, using suitable conventional sizing materials such as above specified. The grease proofing coating is then applied to the hard sized sheet, or on top of the surface sizing, the grease proof coating being thereby prevented from objectionably sinking into the sheet with resultant deterioration.

- providing a bottom liner 47 and a top liner 48. The top liner 48, which is adapted to form the interior of the container and to receive the sheet.

This board as above described may be formed on a conventional cylinder mold machine having a number of molds to form the various layers or plies of the sheet, these plies being brought together and united in 'the ordinary manner. Thus a conveying felt of the forming machine passes first across a cylinder mold containing the bottom liner stock and forms a web, and then passes successively across cylinder molds provided with board stock, asphalt emulsion. board stock, and finally top liner stock to form the complete built-up sheet of container board. The top liner may be surface sized instead of having the size distributed throughout the sheet. After formation, the board is then passed through the coating machine as above described, and a layer of grease proofing composition 49 of the character specified above is applied to the surface of the hard sized grease proof coating, is a hard sized liner, and a final top coat of a water insolu-- ble wax 50 is applied over the grease proofing coat. This sheet is thus protected from water and moisture tending to penetrate from the outside into the interior of the container by the intermediate asphaltic layer, and is made efi'ectively grease proof. water proof and moisture proof by the coating applied to the interior surface of thecontainer.

While the form of invention disclosed herein constitutes a preferred embodiment thereof, it is to be understood that the invention is not limited to this precise form, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims. I

What is claimed is:

1. A paper product of the character described comprising a hard sized sheet having a coating including a polyhydric alcohol, an alkali metal silicate and an alkali metal compound which is alkaline in character, the coating being primarily maintained on the surface of the sheet by the sizing in the sheet.

QJA paper product of the character described comprising a surface sized sheet hav ing superposed upon the surface sizing 1' coating including a polyhydric alcohol and an alkali metal silicate.

3. A paper product of the character described comprising a hard sized sheethaving a flexible surface coating of a grease proofing composition which is primarily maintained on the surface of the sheet by the sizing in the sheet, and a water insoluble wax layer overlying the grease proofing coating.

4. A paper product of the character described comprising a surface sized sheet having 'siiperposed upon the surface sizing a grease proofing composition, and atop layer of a water insoluble wax overlying the grease proofing composition.

5. A paper product of the character described coinprising a sheet having a grease proofing coating of an alkaline composition of a polyhydric alcohol. an alkali metal silic'ate and an alkali metal compound which is strongly alkaline in character.

6. A paper product of the character described comprising a sheet having a grease proofing coating including essentially a pol hydric alcohol and oil insoluble adhesive, t e

polyhydric alcohol being present in an.

amount in excess of 25% by weight on the weight of the oil insoluble adhesive to impart substantial flexibility to the coating.

7. A paper product of the character described comprising a sheet having a grease proofing coating including an alkaline mixture of glycerine and sodium silicate, applied from a solution containing from 60% to 85% by volume of a water solution of sodium silicate containing from 15% to 60% by weight of sodium silicate. and from 15% to 40% by volume of glycerine, and solution also containing a small amount of an a'lkali'metal compound which is alkaline in character.

'8. A paper product of the character described. comprising a container board made up of a plurality of plies of paper withan intermediate asphalt layer, the surface of said board having a grease proofing coating and an overlying coat of a water insoluble wax.

9. A paper product of the character described comprising a container board made up of a plurality of plies of paper with an intermediate asphalt layer. the surface of said container board which is adapted to form the interior of a container having a grease proofing coating including a polyhydric alcohol and an alkali metal silicate, and a coat of a water insoluble wax overlying the grease proofing coating. v

10. A paper product of the. character described comprising a container board made up of a plurality of plies of paper with an intermediate asphalt lay the top liner of said container board which is adapted to form the interior of a container being hard sized and having a grease proofing coating on the surface of said hard sized linerand a coat of a water insoluble wax overlying the grease proofing coating.

11. A container board adapted for the packaging of greasy materials, comprising a laminated sheet made up of a plurality of plies of paper with an intermediate water proofing and moisture proofing layer, one surface of said laminated sheet having a substantially odorless and tasteless non-fibrous grease proofing coating applied thereto and maintained primarily on the surface of the said sheet.

12. container. board adapted for the packaging of greasy materials, comprising a laminated sheet made up of a plurality of plies of paper with an intermediate water proofing and moisture proofing layer, the outer ply of said laminated sheet on the side which is adapted to form the interior of a container being a sized paper having on the exposed surface thereof an overlying grease proofing coating.

13. A container board adapted for the packaging'of greasy materials, comprising a laminated sheet made up of a plurality of plies of paper with an intermediate water proofing and moisture proofing layer, one surface of said laminated sheet having a grease proofing coating and an overlying coat of a water insoluble wax.

14. A container board adapted for the packaging of greasy materials, comprising a laminated sheet made up of a plurality of plies of paper with an intermediate asphalt layer, the surface of saiddaminated sheet which is adapted to form the interior of a container havlng a non-fibrous grease proofing coating applied thereto and maintained primarily on the surface of the said sheet.

15. A board product of the character described comprising a "laminated board made up of a plurality of plies of paper with an intermediate water proofing and moisture roofing layer, one surface of said laminated oard havin a grease proofing coating including an 011 insoluble adhesive and a polyhydric alcohol.

16. A board product of the, character described comprislng a laminated board made up of a plurality of plies of paper with an intermediate asphalt layer, one surface of said laminated board having a multi le' layer grease proofing and moisture proofing coating ap lied thereto.

17. board product of the character described comprising a laminated board made up of a plurality of plies of paper with an intermediate water proofing and moisture pgoofing layer, one surface of said laminated ard having a multiple layer grease proofing and moisture proofing coating applied thereto.

18. A paper product of the character described, comprising a hard sized sheet having a flexible surface coating of a grease proofing composition including an oil insoluble adhesive which covers the exposed surface of the sheet, and which is primarily maintained on the surface of the sheet by the sizin in the sheet to provide a durable grease proo ng coating.

19. A paperproduct of the character described, comprising a surface sized sheet having superposed upon the surface sizing a flexible coating of a grease proofing composition including an oil insoluble adhesive which covers the surface sizing, and which is primarily maintained on the surface of the sheet by the sizing to provide a durable grease proofing coating.

In testimony whereof I hereto aflix my signature.

JOSEPH H. SWAN, III. 

